Dr. Javier Gonzalez-Sanchez [email protected] www.javiergs.info o ffi ce: 14 -227 CSC 305 Individual Software Design and Development Lecture 12. Quality 

Quality Metrics Structural 

Abstractness • Indic a tes whether: ( a ) the item is m a inly a bstr a ct (interf a ces, a bstr a ct cl a sses – extensible but not directly us a ble); or (b) it is m a inly concrete (implement a tions – directly us a ble but less extensible). • It is a v a lue between 0 a nd 1: 0 ( a concrete cl a ss or a p a ck a ge with only concrete cl a sses) 1 ( a n a bstr a ct cl a ss/interf a ce or a p a ck a ge with only a bstr a ct cl a sses/interf a ces) 3 

Instability • Indic a tes whether: ( a ) the item is m a inly used by others (st a ble – h a rd to ch a nge); or (b) it m a inly depends on other items (in-st a ble – ch a nge a ble). • It is a v a lue between 0 a nd 1: • 0 only incoming dependencies to • 1 (only outgoing dependencies). 4 

Distance 5 Abstract Concrete Stable Hard to Change Only incoming dependencies Unstable Changeable Only outgoing dependencies the main sequence Painful Useless 0 1 1 0 Instability Abstractness 

Example 6 Write the Source Code 

Software Metrics Complexity 

Function Metrics • Cyclomatic Complexity. It is a quantitative measure of the number of linearly independent paths. • P a ths occur when "while,” "for,” "if,” "c a se," a nd "goto" keywords a ppe a r within the function. • If the source code cont a ined no control f low st a tements (condition a ls or decision points), the complexity would be 1 • If the code h a d one single-condition IF st a tement, there would be two p a ths through the code: one where the IF st a tement ev a lu a tes to TRUE a nd a nother one where it considers to be FALSE. • Two nested single-condition IFs, or one block with two conditions, would produce a complexity of 3. 8 

Cyclomatic Complexity 9 CC = Edge - Node + 2 Or CC = ConditionalNodes + 1 

Cyclomatic Complexity i = 0; n=4; while (i

Complexity Number Meaning 1-10 Structured and well written code High Testability Cost and Effort is less 10-20 Complex Code Medium Testability Cost and effort is Medium 20-40 Very complex Code Low Testability Cost and Effort are high >40 Not at all testable Very high Cost and Effort Cyclomatic Complexity 11 

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Questions 19 

Lab 

Calculate D, I, A 21 

CSC 305 Individual Software Design and Development Javier Gonzalez-Sanchez, Ph.D. [email protected] Fall 2025 Copyright. These slides can only be used as study material for the class CSC305 at Cal Poly. They cannot be distributed or used for another purpose.